Medfamily team
Medfamily team
1) The resting membrane potential:
a. Is much closer to the equilibrium for Na+ than
to the equilibrium potential for K+.
b. Is much closer to the equilibrium for K+ than to
the equilibrium potential for Na+.
c. Is halfway between the equilibrium potential for
Na+ and the equilibrium potential for K+.
d. Is always negative inside and equal to -90 mV
in all tissue of the body.
e. It is greatly affected by Calcium ion distribution
between inside and outside.
2) Graded potentials:
a. Are local changes in membrane potential that
occur in varying magnitudes.
b. Is always excitatory (produced EPSP).
c. Serve as long-distance signals in neurons.
d. Serve as short distance signals in neurons.
e. Are found only in neuronal potentials.
3) Threshold potential:
a. Is a potential achieved when two opposing
forces acting upon an ion to achieve a state of
equilibrium.
b. Is the peak potential achieved during an action
potential.
c. Is the point at which there is an explosive
increase in Na+ permeability.
d. Is the potential at which the permeability to K+
increases.
e. Is always positive in potential.
4) The membrane is more permeable to K+
than to Na+ at all of the following EXCEPT:
a. At resting potential.
b. During the rising phase of an action potential.
c. During the falling phase of an action potential.
d. During hyper-polarization.
e. During an IPSP signal.
5) Salutatory conduction:
a. Occurs in unmyelinated nerve fibers.
b. Is slower than conduction by local current flow
because of the myelin.
c. Involves the impulse jumping from one node of
Ranvier to the adjacent node.
d. Refers to the action potential spreading from
one myelin-forming cell to the adjacent myelinforming cell.
e. More than one of the above are correct.
6) Which of the following statements
concerning the absolute refractory period is
wrong?
a. It refers to the period of time during which the
neuron can not be stimulated again no matter how
strong the
stimulus.
b. It corresponds to the time period during which
the Na+ gates are first opened and then closed and
inactivated.
c. It assure the unidirectional spread of the action
potential down the nerve fiber away from the
initial site of
activation.
d. It is longer in duration than relative refractory
period.
e. It is much longer for twitch muscle than it is for
neuron.
7) Compound action potential recorded in a
neuronal bundle is due to:
a. Different threshold values for different neurons.
b. Different velocities of conduction in different
neurons.
c. Different action potential amplitudes in
different neurons.
d. Different rate of stimulation in different
neurons.
e. Varying length of the neurons.
8) Which of the following fibers have the fastest
conduction velocity:
a. Autonomic C fibers.
b. Autonomic B fibers.
c. Alfa A fibers.
d. Beta A fibers.
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Medfamily team
e. Gamma A fibers.
9) Acetylecholine receptors in NM junction are
competitively blocked by:
a. Physostigmine.
b. Military nerves gases.
c. Black spider venom.
d. Curare.
e. Clostridium botulinum toxins.
10) Temporal summation:
a. Takes place when two EPSPs from the same
presynaptic input occur so closely together in time
that they add
together or sum.
b. Takes place when an EPSP and IPSP occur
simultaneously in time and cancel each other out.
c. Takes place when two EPSPs that occur
simultaneously from different presynaptic inputs
add together or sum
on the same cell body.
d. Takes place when action potentials occurring in
two presynaptic inputs simultaneously converge
upon the
postsynaptic cell.
e. Occur in smooth muscle only.
11) An IPSP:
a) Is produced by increased permeability to Na+
and K+.
b) Is produced by increased permeability to K+
and or to Cl -.
c) Is a small depolarization of the postsynaptic
cell.
d) Occurs only at synapses but not NM junctions.
e) Both (a) and (d) above are correct.
12) All of the following differences between NM
junction and synapses are correct EXCEPT:
a. Spatial summation is present only in synapses.
b. There is one NM junction on each muscle fibers
but multiple synapses on neurons.
c. Both could have either inhibitory or excitatory
effects on post-junctional fibers.
d. Well organized NM junctions are found only on
skeletal muscle fibers.
e. Myasthenia gravis occurs only in NM junction.
13) Which of the following is the
neurotransmitter in all autonomic ganglia:
a. Nor-adrenaline.
b. Adrenaline.
c. Acetylcholine
d. Nicotine.
e. Muscarine.
14) Which of the following are cholinergic
receptors:
a. Beta 1 receptors.
b. Beta 2 receptors.
c. Alfa 1 receptors.
d. Alfa 2 receptors.
e. Nicotinic receptors.
15) All the following responses are produced by
sympathetic activity (during emergency )
Except:
a. Increased heart rate.
b. Pupil dilation.
c. Broncho-constriction.
d. Release of adrenaline.
e. Constriction of skin blood vessels.
16) Which of the following is wrong about
membrane during resting:
a. Is more permeable to k+ than to Na+.
b. The Na – K+ pump is inhibited.
c. Has negative potential on the inside.
d. Na+ can leak through the membrane to inside.
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Medfamily team
e. Is close to the equilibrium potential of K+.
17) Given log 10=1, log 100=2, log 1000= 3,
calculate the resting membrane potential when
the concentration of
K+ in ECF is 13 mM and in ICF 130 mM:
a. - 80 mV.
b. -62 mV.
c. + 70 mV.
d. +62 mV.
e. – 90 mV.
18) All of the following contribute to the genesis
of the resting membrane potential Except:
a. The Na+ - K+ pump activity.
b. The diffusion of K+ ion down it's concentration
gradient.
c. The diffusion of Na+ ion down it's
concentration gradient.
d. The selective permeability of the membrane to
ions of Na+ and K+.
e. The opening and closing of the Na+ voltage
gated channels during resting.
19) All the following sentences about action
potential are true Except:
a. Is produced by the opening of Na+ and K+
voltage gated channels.
b. Is produced only in cells which has negative
resting membrane potential.
c. In the neurons it is normally generated at the
cell body.
d. Is graded response.
e. Its fast upstroke is produced by influx of Na+
20) Salutatory conduction:
a. Describes fast conduction of action potential in
mylinated neuron.
b. Involves the action potential jumping from one
node of ranvier to the next.
c. Consumes large quantity of ATP.
d. Refers to action potential spreading from one
schwan cell to another.
e. A and B are correct.
21) During depolarization stage of the action
potential:
a. There is net outward current and the cell interior
becomes more negative.
b. There is net outward current and the cell
interior becomes less negative.
c. There is net inward current and the cell interior
becomes more negative.
d. There is net inward current and the cell interior
becomes less negative.
22) The conduction velocity of the nerve fibers
is increased by:
a. Decreased temperature.
b. Increased concentration of the external sodium
ions.
c. Increased axon diameter.
d. Myelination.
23) In the neurone, all are true EXCEPT:
a. The magnitude of the action potential is
dependent on the strength of the stimulus.
b. Impulses can travel in both direction.
c. Depolarization is accompanied by increase
permeability of the cell membrane to potassium
ions.
d. During depolarization the potential of the
neurone may becomes +ve.
24) In the neurone, all are true EXCEPT:
a. Axons convey impulse away from the cell body.
b. Neurotransmitters are synthesized in cell bodies
and then transported to the axons.
c. The conduction velocity increase with fiber
diameter.
d. There is an influx of Na+ and efflux of K+
during depolarization.
25) One of the following is not true regarding
action potential:
a. Initiated by depolarization.
b. Has magnitude dependent on stimulus strength.
c. Accompanied by decrease in electrical
resistance of the membrane.
d. Can travel in rather direction.
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Medfamily team
e. Has a peak which depends on the external
sodium concentration.
26) All of the following are important in
producing resting membrane potential
EXCEPT:
a. Na+ / K+ pump.
b. The presence of negatively charged proteins
inside the cell.
c. The selective permeability of the cell
membrane.
d. The passive diffusion of K+ ions.
e. All of the above.
27) During the fast depolarization phase of the
action potential, the membrane permeability
to:
a. K+ is much greater than that to Na+
b. Na+ is much more than that to K+
c. Both Na+ and K+ are equal.
d. Cl- is highest than any other ion.
e. Ca++ is highest than any other ions.
28) Propagation of a nerve action potential:
a. Occurs by local circuits in the myelinated
nerves.
b. Is faster in the unmyelinated nerves.
c. Occurs by salutatory conduction in the
myelinated nerves.
d. Does not need energy.
e. None of the above is correct.
29) At overshoot of the nerve action potential:
a. All K+ channels close.
b. All Na+ channels open.
c. All Na+ channels close.
d. All Cl- channels open.
e. All of the above are correct.
30. Which of the following characteristics of an
axon is most dependent on
its diameter?
a. The magnitude of its resting potential
b. The duration of its refractory period
c. The conduction velocity of its action potential
d. The overshoot of its action potential
e. The activity of its sodium-potassium pump
31. If the extracellular K+ concentration is
increased from 4 meq/L to
10 meq/L,
a. The membrane potential will become more
negative
b. The sodium conductance will increase
c. The potassium conductance will increase
d. The membrane will become more excitable
e. The Na-K pump will become inactivated
32. Inactivation of the sodium-potassium pump
will cause
a. An increase in the intracellular volume
b. An increase in the intracellular potassium
concentration
c. Hyperpolarization of the membrane potential
d. An increase in the excitability of nerve cells
e. An increase in the flow of sodium out of the cell
33. Membrane excitability will be increased by
the greatest amount by
a. Increasing extracellular Na+
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Medfamily team
b. Increasing extracellular K+
c. Decreasing extracellular Cl2−
d. Decreasing extracellular Ca2+
e. Decreasing extracellular H+
34. The resting potential of a nerve membrane
is primarily dependent on
the concentration gradient of
a. Potassium
b. Sodium
c. Calcium
d. Chloride
e. Bicarbonate
35. Which of the following words or phrases is
most closely associated
with an end-plate potential at the
neuromuscular junction?
a. “All-or-none response”
b. Depolarization
c. Hyperpolarization
d. Action potential
e. Electrically excitable gates
36. In a nerve, the magnitude of the action
potential overshoot is normally
a function of the
a. Magnitude of the stimulus
b. Intracellular potassium concentration
c. Extracellular sodium concentration
d. Resting membrane potential
e. Diameter of the axon
37. The velocity of nerve conduction is
increased with a decrease in the:
a. Diameter of the nerve fiber
b. Degree of myelinization
c. Space constant of the nerve fiber
d. Capacitance of the nerve fiber membrane
e. Resting membrane potential
38. The membrane potential will depolarize by
the greatest amount if the
membrane permeability increases for:
a. Potassium
b. Sodium and potassium
c. Chloride
d. Potassium and chloride
e. Sodium
39. Which of the following will be less during
the overshoot of an action
potential than during the resting state?
a. Membrane conductance for sodium
b. Membrane conductance for potassium
c. Transference for sodium
d. Transference for potassium
e. Total membrane conductance
40. Preventing the inactivation of sodium
channels will decrease
a. The relative refractory period of nerve cells
b. The upstroke velocity of nerve cell action
potentials
c. The downstroke velocity of nerve cell action
potentials
d. The magnitude of the overshoot in nerve cell
action potentials
e. The duration of nerve cell action potentials
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Medfamily team
41. An increase in sodium conductance is
associated with:
a. The plateau phase of the ventricular muscle
action potential
b. The downstroke of the skeletal muscle action
potential
c. The upstroke of the smooth muscle action
potential
d. The refractory period of the nerve cell action
potential
e. The end-plate potential of the skeletal muscle
fiber
42. The sodium gradient across the nerve cell
membrane is
a. A result of the Donnan equilibrium
b. Significantly changed during an action potential
c. Used as a source of energy for the transport of
other ions
d. An important determinant of the resting
membrane potential
e. Maintained by a Na/Ca exchanger
43. Increasing the extracellular potassium
concentration will
a. Increase the threshold for eliciting an action
potential
b. Hyperpolarize the membrane potential
c. Decrease potassium permeability
d. Decrease the activity of the sodium-potassium
pump
e. Make the equilibrium potential for potassium
more negative
44. Which of the following would cause an
immediate reduction in the
amount of potassium leaking out of a cell?
a. Increasing the permeability of the membrane to
potassium
b. Increasing the intracellular potassium
concentration
c. Increasing (hyperpolarizing) the membrane
potential
d. Reducing the activity of the sodium-potassium
pump
e. Decreasing the potassium equilibrium potential.
Medfamily team
Medfamily team
1 B 21 D 41 E
2 A 22 D Not sure 42 C
3 C 23 C 43 A
4 B 24 D 44 C
5 C 25 C Not sure
6 A 26 D
7 B 27 B
8 C 28 C Not sure
9 D 29 B
10 A 30 C
11 B 31 C
12 C 32 A
13 C 33 D
14 E 34 A
15 C 35 B
16 B 36 C
17 B 37 D
18 B 38 E
19 D 39 D
20 E 40 C